For some reason on a Cisco WAP571, the SNMP value returned from apRadioNumAssociatedStations is always zero.
This is true on firmware tested WAP571 (pgwap571, 1.1.0.3).
I have a few of these units around that are not updated to the latest firmware and will test that OID.
I can find data in the apAssocTable to create indexes. For now I’ve created a hack to just snmptable the apAssocTable and count return index values to then pass to Cacti to graph.
snmptable -Cl -CB -Ci -OX -Cb -Cc 16 -Cw 64 -v2c -c <community> <host:port> CISCO-WLAN-ACCESS-POINT-MIB::apAssocTable | grep index | wc -l